It is common practice to package beverages such as sparkling fruit juices, cola drinks, beers and the like in cans, typically being manufactured from pressed aluminium or plated steel, the thickness being of the order of 50 μm or so. These cans are typically sold in four- or six packs. Early examples of packaging such packs utilised cardboard which enveloped the cans. In the 1950's plastic film container carriers were first promulgated. The early forms of plastics film container carrier utilised apertures which were deformed upon application of the sheet over the cans, whereby the film formed a continuous flange area about the side of the can. The films were placed about the top of the can, underneath a beaded edge formed at the junction of the lid of the can.
Such early forms of carrier film allowed the cans to be pulled through—albeit with some difficulty—but a reverse movement of the can with respect to the carrier would mean that the plastics flange would abut the bead and further movement required a considerable force to release the can.
FIG. 1 shows an example from U.S. Pat. No. 2,874,835 (ITW) which provides a carrier 30 comprising a flat sheet of plastic material which is provided with a plurality of apertures 32. The apertures are distinctly smaller (>20%) than a diameter of a can retained by the carrier. FIG. 1a shows how cans, in use are retained, with the circumferential inner edge of the plastics apertures engaging with a lower edge of rim 46. It can be seen that the plastics carrier material is substantially deformed by stretching—after considerable forces have been applied—such that the edge of the aperture is perpendicular to the plane of the plastics carrier period to placement of the cans, especially with reference to feature 40 in FIG. 1b. Indeed, we are advised that it is substantially impossible for the cans to come loose from the retainer device accidentally. We are advised that the use of polyethylene is a preferred plastics material, which is stamped in a press to form the apertures. This example taught of additional holes through which the ends of an elongate handle can subsequently be inserted. These plastics films—commonly referred to as carrier stock—are stretched beyond their elastic limit. That is to say the size of aperture will in turn stretch into shapes which are complimentary to the shapes of the container (per U.S. Pat. No. 4,250,682 (ITW)). The carrier stock is typically polyethylene and early examples were of a thickness of 500 μm or more, although it is typically 400 μm or more for rim applied carriers.
The forces necessary to enable the plastics film to engage with the sides of a can were considerable and, of course, the large forces that were utilised to pack the containers together resulted in problems in a consumer accessing an individual tin. GB1200807 (ITW) introduced slits in apertures, but forces of application were still considerable since the apertures were “significantly smaller than the diameter of a can with which the carrier film is to be assembled” and therefore were still stretched beyond the elastic limit of the material. U.S. Pat. No. 2,997,169 taught of a solution to the problem by the inclusion of tear-off tabs 72b; per FIGS. 2a & 2b, where pre-stressed members associated with tab portion enabled a tear in the plastics retaining film, which was considered easier than forcing the rim of the can around the already stretched plastics film.
The cans are of a greater diameter than the apertures and, accordingly, stretch the apertures and deform the material adjacent into a frusto-conical shape whereby the cans are aggressively retained against withdrawal in the direction opposite to that in which they have been inserted . . . .”. U.S. Pat. No. 2,936,070 teaches of a still further patent, the teaching of which was to address that a plastic carrier that provides a gripping section not susceptible to loss of a can through twisting and bending movements. With reference to FIGS. 3a and 3b, resilient, flexible fingers 28 were forced upwardly (as the plastics film is placed upon a number of cans during packing), the fingers being determined by roots 30 defined partway into an inside edge portion of an aperture. FIGS. 3b and 3c show the teaching from this prior retainer in side views, where the rounded crenulations 28 are clearly visible. U.S. Pat. No. 2,936,070 advises, in particular, that the root diameter is less than the diameter of the cans and a considerable stretching force is, nonetheless, applied to the plastic material in the vicinity of the roots in stretching the material into the frustoconical, almost cylindrical conformation shown in FIG. 3c. The description further discloses that “the carrier can be assembled with cans with considerable facility, simply by stamping the carrier down over the proper number of cans. The cans simply cam into the apertures, deflecting the fingers . . . whereby the cans are gripped aggressively with the fingers abutting beneath the can beads”. Indeed, the stamping forces would have been considerable.
Further developments included various modifications: one proposal for an article carrier was formed from a tube which was alternately slit from side-to-side in a manner leaving un-slit connecting portions at subsequent alternate opposite sides whereby successive sections of the tube may be folded relative to each other generally into a common plane for receiving the articles to be carried. In order to economize on material, it is generally desirable to make the wall of the tube as thin as possible consistent with the required strength and durability. Thus, in such heretofore proposed structures, immediately adjacent articles in a package are spaced from each other at the area of contact with the carrier only by a double thickness of the relatively thin material. It was found that such spacing is, for many purposes, insufficient since, in practice, the closely adjacent articles such as bottles or cans would rub against each other so that the respective surfaces may be scratched or otherwise defaced. For example, it is common practice to apply a label or other decorative design by lithography or other means to beverage cans and such labelling would be damaged if the cans were permitted to rub together unduly such as when the package was subjected to continual motion or vibration during transport. U.S. Pat. No. 3,924,738 provided a solution to this problem by forming longitudinally extending rib means whereby to provide a separation spacing between cans, as shown in FIG. 4.
U.S. Pat. No. 3,968,621 taught of manufacturing a carrier by the formation of an extruded net, which net was subsequently flattened by the use of a roller to produce an apertured film of carrier stock, as shown in FIG. 5. U.S. Pat. No. 3,317,234 teaches of a packaging system using an upper laminate and a lower laminate. As seen with reference to FIGS. 6a and 6b, the upper laminate comprising a first, continuous plastics layer and a second laminate comprising an apertured card layer is placed over an arrangement of bottles. The apertures of the card layer are arranged to fit over respective metal cap of a drinks bottle, the peripheral edges of the apertures being arranged to engage with the underside of the metal cap, whereby to retain the upper part of the bottle. The lower laminate being arranged to act in a similar fashion with a bottle having a characteristic waist, about which a card member of the second laminate could engage, in conjunction with a plastics layer, which enveloped a lower portion of the bottle. In a similar fashion, cans were retained by substantially similar first and second laminates, the card element of which engaging with a body-directed edge of the respective upper and lower rims of a double rimmed can.
In the early 1980's, there was a shift in the method of applying film stock to cans and the like. Previous forms of strip stock for circularly cylindrical containers had been provided with substantially circular apertures. In contrast teachings equivalent to or derived from U.S. Pat. No. 4,219,117 (ITW), which were designed for application by dedicated jaw and drum machinery (such as described in U.S. Pat. No. 4,250,682) utilised stock that had integrally joined band segments defining can receiving apertures in longitudinal rows and transverse ranks. The band segments included generally longitudinal outer segments with each outer segment partly bounding the can receiving apertures in an outer row. The apertures defined in such stock are generally of a triangular/D shape, primarily to assist in the mechanical placement of the stock around the rim of a can, which mechanical application necessitated the use of mechanical fingers which generally prevented the simultaneous use of such devices in any configuration other than in the provision of two-rank longitudinal rows. That is to say the cans are attached with two cans being in a side-by-side arrangement: the systems generally could not reliably operate to provide cans packed, for example in 3×3 or 3×4 or 4×4 etc arrangements.
In the carrier stock illustrated and described in the U.S. Pat. No. 4,219,117, the band segments also included inner segments partly bounding the can-receiving apertures, along with transversely extending segments joining the inner segments, for finger-hold grip elements.
Can manufacturers have in the past introduced cans having smaller chime diameters, as compared to the diameters of the side walls. Cans of this type are known as “necked-in” cans. The newest versions of these necked-in cans further and drastically reduce the ratio of the chime diameter and the side wall diameter. When stock is applied by known procedures, the band segments defining the can receiving apertures grip the frusto-conical walls of the cans tightly and engage the lower edges of the chimes.
In a necked-in can of a newer type, the frusto-conical wall between the chime and the side wall defines a conical angle greater than approximately 28° and in some instances as great as approximately 37°. When the frusto-conical wall defines such a large angle relative to the can axis, it is difficult to apply carrier stock since the band segments defining the can receiving apertures have an undesirable tendency to slide up the cans and to rest on the cans above the lower edges of the chimes. This tendency is enhanced due to the jaw application system mentioned above.
A further problem of known systems, where great forces have been used to apply the carrier stock, that they can be difficult to remove—not only by accident; in use, especially by youngsters, has caused effervescent spillage to occur since the removal by force of a drinks can from a carrier strip has resulted in an unnecessary disturbance of the effervescent liquid inside, resulting in a spray or spillage upon a subsequent opening of the can. In EP0461748(ITW) and EP0621203 (ITW)—which address the provision of tear-open tabs, which extend upwardly across the chimes of straight-walled and conical cans, respectively, whereby to simplify release. The tabs in the later patent have concave lateral portions adjacent a stem of the tab “for stress relief”. Furthermore, both these documents involve the use of relatively thick (greater than 400 μm) and in placement around cans are stretched beyond their elastic limit. These types of carrier stock have not, however, been widely adopted. This utilises a thick plastics sheeting which is stretched beyond its elastic limit.